Figure 6-37.Fresnel® lens optical landing system (FLOLS).
line. They are spaced 1,000 feet apart. The signs have
painted numbers that are lit so they can be seen at night
and during periods of restricted visibility.
The power supply for serving the runway distance
markers should be from a separate series circuit. Do not
THRESHOLD LIGHTS.The threshold lights
are a part of the approach light system. Four sets of
light systems are used in the threshold light
configuration. These lights are as follows: inboard
threshold lights, winged-out threshold lights,
prethreshold wing bars, and a terminating bar. These
have the markers supplied from circuits feeding either
four sets of lights are installed on both ends of the
the runway, threshold, or the approach lighting
runway and are used to mark the beginning of the
circuits, since these circuits are operated at various
brightness steps, and the signs are operated at their full
brightness at all times. Also, do not connect them to
Inboard Threshold Lights.Inboard threshold
taxiway circuits because of the intermittent operation
lights are installed in the area at the end of the runway
between the two runway edge light lines. This line of
requirements. The cable used for the runway distance
marker circuit is a single conductor, No. 8 AWG,
stranded, 5,000 volts.
lights will be at a right angle to the runway center line.
They arc as close to the full-strength paving as
possible but not more than 10 feet from it. The lights